Built-From-Scratch Self-Balancing Inverted-Pendulum Wheelie-Popping Remote-Controlled Vehicle March 14, 2008 Jude Collins Christopher Madsen.

Built-From-Scratch Self-Balancing

Inverted-Pendulum Wheelie-Popping

Remote-Controlled Vehicle

March 14, 2008

Jude CollinsChristopher Madsen

Preliminary Design Presentation

➲ Technical aspects of the robot➲ Literature/Patent search➲ Schedule➲ Finances

Overview

➲ Robot system overview—Chris Microcontroller Inertial measurement unit Bluetooth radio H-Bridge/Motors

➲ Remote control—Jude Microcontroller Bluetooth radio N64 Controller

Overview

➲ Literature/product search—Chris “Trajectory Tracking Control for Navigation of

Self-contained Mobile Inverse Pendulum” (1994).

Segway (2002). David P. Anderson's “nBot” (2003).

➲ Schedule and finances—Jude➲ Questions

Robot system overview

Robot system overview

Microcontroller

➲ MSP430F1611➲ Running 4 MHz➲ 12 bit A/D with 8 pin-

accessible inputs➲ Two 16 bit timers➲ 1.8-3.6v

Inertial Measurement Unit

➲ IDG-300Gyroscope

➲ ADXL-330Accelerometer

IDG-300 Gyroscope

➲ Dual-Axis rate gyroscope➲ Operates by oscillating masses and

capacitively measuring vibration caused by Coriolis effect.

➲ Sensitivity: 2 mV/deg/s➲ Max rate: 500 deg/s➲ Operating voltage: 3.0-3.3v

ADXL-330 Accelerometer

➲ Triple-axis accelerometer➲ Micro-machined structure suspended

over silicon by polysilicon springs. Plates mounted on moving structure and a fixed structure act as a variable capacitor in a filter circuit to measure acceleration.

➲ Sensitivity: ~300mV/g➲ Max acceleration: ±3.0g➲ Operating voltage: 2.0-3.6v (sensitivity is

ratiometric)

PID Controller

Estimating pendulum orientation➲ Integrating rate gyros is

subject to drift errors.➲ Accelerometers only work

to determine orientation when not accelerating.

➲ Use both estimates to get better estimate of orientation.

Bluetooth Radio

➲ Basically a breakout board for NXP's BGB203.

➲ Class 1 so has a 100m range

➲ 100 mW max transmitted power

➲ 3.3 volts➲ 1 Mbps max UART

H-Bridge

➲ LMD-18200➲ 3 amps continuous, 6 amps temporary

Remote Control

The Remote Control

➲ Needed Peripherals Joystick A few buttons

➲ Modify old N64 controller. Exceeds requirements Cheap ($5-$15 on

Amazon.com)

Control Flow

The microcontroller

➲ Needed peripherals UART fclk > 1 MHz Low Vcc

➲ ATMEGA8515L Already had the chip. UART 20 MHz 2.7 – 5.5 V Low Cost ($3.06-$5.27 Digikey.com)

N64 Controller Interface

➲ Bidirectional data line.➲ PWM - 1:3

Micro sends poll request. Bit-Bang 32 bit response.

➲ Fixed Frequency Poll and Transmit ~20 Hz

Data Line PWM

Literature/patent search

➲ First appearance of similar two-wheeled inverted pendulum that can navigate in 2 dimensions on a plane: “Trajectory Tracking Control for Navigation of Self-contained Mobile Inverse Pendulum” by Yunsu Ha and Shin'ichi Yuta of Japan in 1994.

Position encoders on wheels (2000 step) Sensors to detect obstacles No remote-control

Literature/patent search

➲ Segway Most popular inverted-pendulum type product. Patented just about everything imaginable

concerning inverted pendulum human transportation.

Have several Robotic Mobility Platform (RMP) models

Literature/patent search

➲ David P. Anderson's nBot Received NASA's Cool Robot of the Week award and

subsequently became well-known in the minds of robotics enthusiasts (2003).

Launched a revolution of inverted-pendulum robot building.

Homebrew shaft encoders.

How are we different?

➲ Back EMF encoders rather than mechanical encoders.

➲ Bluetooth radios enabling hardware-in-the-loop simulation.

➲ Goal to stand up autonomously.

Schedule

Date Goal (Wireless controller) Goal (Robot)February 8, 2008 Functioning prototype robotFebruary 15, 2008 N64 Controller prototype Math model complete

February 22, 2008 N64 Controller testing complete Decision on use and design ofencoders

February 29, 2008 Make provisions for wireless controllercommunications

March 7, 2008 N64 Controller communicationscomplete

N64 Controller communicationscomplete

March 14, 2008 Preliminary Design Presentation Preliminary Design Presentation

March 21, 2008 Incorporate other wireless devices(PDAs, etc)

Robot can lay itself down gently

March 28, 2008 Robot can "pop a wheelie"April 4, 2008 Bigger batteries?April 11, 2008 Final Testing - Hand it over to mom.April 18, 2008 Demonstration Demonstration

Finances—RobotItem Type Quantity Individual Price Item Total

Gearhead Motors 12v Globe Motors #415A410 2 ~$25.00 ~$50.00

Wheel Mounts 5mm RC Airplane propellerholder

2 ~$8.00 ~$16.00

Wheels 15500 Golden Age5" (WBR15500) 2 (one pack from RC hobbies) $13.23 $26.46

Frame Aluminum (L shaped and flatpieces from Home Depot) ---- ~$3.00 ~$10.00

Microcontroller MSP430 (on Softbaugh B169breakout board) 1 $49.00 $49.00

Bluetooth Controller Sparkfun WRL-08461breakout board based onNXT's BGB203

1 $59.95$59.95

Inertial Measurement Unit

Sparkfun SEN-00741breakout board based onAnalog Device's IDG300 2axis rate gyro and ADXL330 3axis accelerometer

1 $109.95 $109.95

H-Bridge LMD18200 2 $14.40 $28.80

Voltage Regulator LM317 1 ~$1.00 ~$1.00

Resistors and capacitors ---- ~$1.00 total $1.00

Batteries NiCd 9.6v batteries 2 $8.00 $16.00

Total: $368.16

Finances—Remote Control

Item Type Quantity Individual Price Item Total

Nintendo64 Controller Original Nintendo 1 ~$10.00 ~$10.00

Bluetooth Controller Sparkfun WRL-08461breakout board based onNXT's BGB203

1 $59.95 $59.95

Voltage Regulator LM317 1 ~$1.00 ~$1.00

BJT Transistor 2N3904 1 ~$1.00 ~$1.00

20 MHz Crystal Oscillator ?? Japan Made 1 $2.00 $2.00

Capacitors and Resistors ----- ----- ----- ~$1.00

Microcontroller ATMEGA8515L 1 $5.27 $5.27

Total: $80.22

Finances

➲ Allotted budget: $1000➲ Expenditures: ~$500➲ Main expenses:

1 IMU -- $110 2 Bluetooth radios -- $120 1 MSP430 on breakout board -- $50 2 Motors and H-Bridges -- $80

Questions?

Simple inverted pendulum model

Simple inverted pendulum with force input

H-BridgeDirection Control

➲ Forward➲ Reverse➲ Brake➲ Short Circuit

H-BridgeAmplitude Control